As an apparatus which performs an opening/closing operation by rotating an opening/closing body, such as a tailgate or an out-swinging window of an automobile, an apparatus to open and close an opening/closing body (hereinafter, may be referred to as “opening/closing body opening and closing apparatus”) has been known. An opening/closing body opening and closing apparatus illustrated in Patent Literature (hereinafter, referred to as “PTL”) 1, for example, includes an actuator section which is extendable and contractible by driving force of a built-in motor, and this opening/closing body opening and closing apparatus is an apparatus which opens and closes the opening/closing body attached in an openable and closeable manner to a main body of an automobile or the like, by using extension and contraction of the actuator section.